Nitrogen addition drives local extinction of legumes in meadow steppe

作者：Yinliu Wang, Guoxiang Niu, Kathrin Rousk, Guojiao Yang, Liangchao Jiang, Muqier Hasi, J.J. Xue, Xiao‐Tao Lü, Yong Jiang, Xingguo Han, Ang Li, Jianhui Huang · 发表于：Journal of Ecology · 年份：2025 · DOI：10.1111/1365-2745.70091 · 被引用次数：4 · 研究领域：Ecology and Vegetation Dynamics Studies、Legume Nitrogen Fixing Symbiosis、Agronomic Practices and Intercropping Systems

Abstract Nitrogen (N) enrichment poses a critical threat to legume diversity through three interlinked mechanisms: stimulating growth of non‐leguminous competitors, enhancing community canopy coverage and inducing light limitation. Canopy management practices such as mowing may partially mitigate these impacts by reducing species dominance and restoring light availability. Through a decadal field experiment in a meadow steppe, we systematically investigated the interactive effects of chronic N addition and mowing regimes on legume biomass dynamics and species persistence. Our findings demonstrate a time‐dependent relationship between N enrichment and legume species richness. Most legume species, particularly rare and subordinate ones, were eliminated at intermediate‐to‐late stages when N addition rates exceeded 10 g N m −2 year −1 . This collapse correlated with the progressive suppression of legumes by biomass accumulation in the dominant non‐legume species, Leymus chinensis . Beyond this ecological threshold, only Thermopsis lanceolata persisted in the community, though its biomass ultimately declined with increasing N inputs and associated metal element uptake. Greenhouse experiments revealed this species' survival strategy involves rapid downregulation of N fixation capacity—a potentially critical functional trait distinguishing it from other legumes in the study site. Mowing partially counteracted N‐induced biodiversity loss at sub‐threshold enrichment levels (i.e. < ...